Drum type machine for forming shell molds



Oct 9, 1956 P. KLAMP ET AL DRUM TYPE MACHINE FOR FORMING SHELL MOLDSFiled Feb. 21. 1951 5 Sheets-Sheet 1 IN VEN TOR 5 K4 EMF a. E/GHOP m aw. P w w hm Oct. 9, 1956 P- KLAMP ET A; DRUM TYPE MACHINE FOR FORMINGSHELL MOLDS Filed Feb. 21. 1951 s Shets-Sheet s m m Wm INVEN A TORS PzwzAAMP BY 1. .1 5/6/90) Oct. 9, 1956 P. KLAMP ET AL DRUM TYPE MACHINE FORFORMING SHELL MOLDS Filed Feb. 21, 1951 s Shets-Sheet 4 INVENTORJ PAM/L#4444:

Get. 9, 1956 P. KLAMP ET AL 2,765,506

DRUM TYPE MACHINE FOR FORMING SHELL MOLDS Filed Feb. 21 .1951 5Sheets-Sheet 5 United States Patent 2,765,506 DRUM TYPE MACHINE FORFORMING SHELL MoLns Paul Klamp, Detroit, and Leonard J. Bishop,Birmingham, Mich., assignors to Mechanical Handling Systems, Inc.,Detroit, Mich, a corporation of Michigan Application February 21, 1952,Serial No. 272,796 1 Claim. (Cl. 22-20) This invention relates toimprovements in the construction of a drum-type machine for formingmolds by the foundry process known as shell molding, which processinvolves depositing a layer of a thermo-settiug, finely powdered moldingmaterial upon a heated pattern plate. The thermo-setting material isthen cured upon the pattern plate to form a shell-like mold, which isremoved from the pattern plate and used in a cope or drag for forming acasting.

It has been found extremely desirable, in performing this shell moldingprocess, to employ some form of mechanism by means of which a patternplate could be brought to a container filled with the mold formingmaterlal, have a coating of this material deposited thereon, with thecoated pattern plate then being passed through an oven to cure thethermo-setting molding material, the cured mold removed and the patternplate then brought back to the container in a heated condition forreceivmg the next coating. The present invention relates to a machinefor accomplishing these steps, and this machine has been designated adrum-type, due to the fact that the container, in which the finelypowdered mold formmg material is placed, is a rotating drum equippedwith a number of faces each adapted to receive a pattern plate, thesefaces being open so that the material contained within the drum isdeposited upon the pattern plate as the latter moves around the lowersegment of the horizontal axis on which the drum rotates. Such rotatingdrums have been employed for many years for depositing a layer ofcoating material. For example, in the brick molding art, the mold iscustomarily coated with a layer of sand which serves as a parting agentto facilitate the removal of the wet brick from the mold. Rotating drumshave frequently been employed to perform this coating operation, anearly example being contained in United States Patent No. 385,790.

Consequently, the use of such a rotating drum broadly in a machine ofthis type constitutes no part of the present invention. Likewise, noclaim of invention is made to the broad combination in the presentmachine of such a drum and a curing oven, for the employment of such anoven is dictacted by the very nature of the shell molding processitself. The combination of a rotating drum, curing oven, and means forconveying coated patterns from the drum to the oven and back to thecoating station in a continuous path also forms no part of the presentinvention. Such machines for continuously performing the various stepsrequired in the shell molding process have been designed and are beingemployed commercially at the present time.

The present invention rather consists in certain improvements in thegeneral arrangement of a machine of this type together with improvementsin the'constructional features of the component parts thereof, .all ofwhich improvements together contribute to the successful performance bythe machine of its intended function. The following brief discussion ofthe shell molding process is included for a more thorough understandingof the nature of the steps involved and some of the critical factorswhich arise in the successful performance of these steps by mechanizedequipment.

In the shell molding process, certain problems exist 2,765,506 PatentedOct. 9, 1956 "ice which affect the employment of a drum type containerfor depositing a layer of mold-forming material upon a pattern plate.The material is a very finely divided pulverant whose agitation createsa serious dust problem; this material, which contains a thermo-settingresin, will adhere to any heated surface; and, it must be kept in a veryfinely divided state in order that a uniform smooth coating of materialwill be deposited on every surface of the pattern plate. Thus, in theshell molding machine of the present invention means have been includedto establish a firm positive seal between the pattern plate and thedrum; to minimize and control the heat transfer from the oven and thepattern plate to the drum; and to insure the material being maintainedin a finely divided state and to trap any lumps of molding material sothat they will not be deposited upon any pattern plate.

Upon the completion of the operation of depositing a coating of moldforming material upon the pattern plate, a critical state exists untilthe time this pattern plate has passed through the oven and the moldforming material has thus been cured. Until the curing has beencompleted it is quite easy for the mold forming material to becomedislodged from any portion of the pattern. Means have been incorporatedin the present invention to bring the pattern plate to a level positionas soon as possible after its removal from the rotating drum andmaintain the pattern plate in this level position until the curingprocess has been completed.

Other improvements incorporated in the invention include a relationshipbetween the pattern plate carrier and the drum which permits the formingof molds with a maximum amount of draw for a given size of the parts;and an improved construction of the pattern plate carrier whichcontributes to a proper sealing engagement between the pattern plate andthe drum, and which permits the easy mounting of pattern plates upon thecarrier.

An improved combination of pattern plate carrier, drum, and conveyingmeans for mounting a plurality of carriers and propelling them intoengagement with the drum, holding them in engagement with the drum, andconveying them from the drum in a controlled position through the oven,also constitutes part of the invention.

All of the foregoing improvements, and others which will be brought outin the more detailed description of the invention to follow, aredisclosed in the machine illustrated in the accompanying drawings whichcomprise the following views:

Fig. 1, a semischematic side elevation of the machine, partly insection. This view is intended to illustrate the relationship betweenthe essential operating components of the machine, and for the sake ofclarity, many of the structural details such as a complete disclosureor: supporting framework, drive mechanism and a detailed show ing ofeach of the carriers, have been eliminated. Many of these details arebrought out and their relationship will be explained in connection withother views. Other details are design features which could be suppliedby anyone skilled in the art.

Fig. la, a schematic layout of driving mechanism for the machine of Fig.1.

Fig. 2, a sectional view taken along the line 2-2 of Fig. 1 showing atypical cross-section through the oven portion of the machine, andillustrating a typical relationship between the operating parts thereof.I

Fig. 3, a sectional view taken along the hue 3-3 of Fig. 1 to show theconstruction of the drum element thereof.

Fig.4, a section taken along the line 4-4 of Fig. 3 showing a sideelevation of the drum construction and the relationship between thedrum, a pattern plate and a pattern plate carrier.

Fig. 5, a fragmentary end view of the drum construe tion and mountingtaken in the direction of the arrows 5-5 shown on Fig. 3.

Fig. 6, a sectional detail-taken along the line 6-6 of Fig. 5.

Fig. 7, a plan view of the construction of a pattern carrier and showingthe relationship between the carrier and the conveying chain.

Fig. 8, a section taken along the line 8-8 of Fig. 7.

Fig. 9, a section taken along the line 9-9 of Fig. 7.

Fig. 10, an end view, partly in section, showing the relationshipbetween a carrier, a pattern plate assembly supported thereby, whensectioned along the line 10-10 of Fig. 7, and the various componentparts when this carrier is passing the knockout station of the machine.This view can be correlated with the showing of Fig. 1 by reference tothe line 10-10 indicated thereon, which line illustrates the location ofthe section taken through the machine to show the supporting structureillustrated in this view.

For convenience, the following detailed description of the machine willbe broken down into sections. The general arrangement and majorcomponent parts of the machine will first be described, principally withreference to Figs. 1 and 2. This description will be followed bydetailed descriptions of the major component parts, namely, the drum,the pattern carrier and the pattern plate assembly. The operational andconstructional features of the machine resulting from the generalarrangement and combination of these component parts will then bebriefly reviewed.

Machine in general A comparison of Figs. 1 and 2 will show that themachine is partially encased within a rectangular oven having a top wall10, side walls 11, end walls 12, and a sectional bottom wall composed ofleft and right end portions 13 and 14, respectively, and an internalbafile 15. All these parts are composed of insulating material, thebafile 15 being thinner in cross section than the outer walls of theoven, and extending across the oven'between the side walls 11 at a pointabove the level of the bottom wall end portions 13 and 14. The right endwall includes a downwardly movable access panel 23.

Suitable framework is provided to support the walls of the ovenstructure as well as the operating components of the machine. For thesake of clarity, this framework structure has not been shoum in detailbut the disclosure of Figs, 1 and 2 do include a skeletonizedrepresentation of a portion of the framework necessary for the propersupport of the oven and operating parts. The disclosure of Fig. 2includes a pair of upper longitudinal side beams 16 which areinterconnected by a suitable number of upper cross members 17. Theseupper longitudinal beams 16 are supported at each end by corner uprightmembers 22 which in turn rest upon the upper flange of a pair of lowerlongitudinal I beams 18, interconnected by a suitable number of crossmembers such as the channel member 19 shown in Fig. l, and supportedupon a series 9f,posts.20...whichextend to floor level 21.

H The direct propelling members of the machine consist of a pair ofroller type conveyor chains 25, which travel in a counterclockwisedirection as the machine is viewed in Fig. 1, driven by a pair ofdriving sprockets 26 located at the right-hand end of the machine andkeyed to a common cross shaft 24. The chains travel around a pair oftake-up sprockets 27 which are mounted upon stub shafts 28 carried by amovable take-up framework 29. The construction of this movable frameworkis not shown in detail, as it follows conventional conveyor practice.Position of the take-up frame 29 is controlled by a fluid pressureoperated cylinder (not shown) acting through a rod 30 connected to themovable framework 29 by a suitable bracket 31.

The path of travel of each conveyor chain is defined by a track member35, rectangular in cross section, which engages the flanged rollers 36of the chain. T'hese tracks extend upwardly in the direction of travelaway from the driving sprockets 26, then extend horizontally to thetakeup sprockets 27 and again horizontally across a portion of the lowerpart of the oven. Just below the oven bafiie member 15, the track turnsinto a downwardly directed portion 39 which trains each chain onto asprocket 40 carried by the structure of a four-sided drum 41 which ismounted for rotation on a horizontal axis. Movement of the conveyorchain thus imparts rotary motion to the drum.

A series of equally spaced pattern carriers 45 are each connected to thepair of conveyor chains 25 by a cross bar 46, as can be seen from theenlarged showing of one of these pattern carriers contained in Fig. 7.In Fig. 1, each carrier 45 is shown supporting a pattern plate 48 havinga representative deep draw form, and with the exception of the carrierin engagement with the lower face of the drum 41, the carrierconstruction is not g-ivcn in detail except to indicate that eachcarrier is equipped with a pair of supporting wheels 49. The connectionbetween each carrier and the chain is a pivotal one, and the supportingwheels 49, in addition to carrying the major portion of the weight ofthe carrier, define its position about the. pivotal axis of attachmentbetween the cross bar 46 and the chain. The supporting wheels 49 of eachcarrier travel along a pair of supporting tracks 50 located inwardly ofthe chain supporting tracks 35. Thus, by establishing a properrelationship between the path of travel of the chain supporting tracks35 and the carrier supporting tracks 50, the attitude of the carrier canbe controlled for proper approach of the pattern plate 48 intoengagement with a face of the drum 41, to maintain a proper sealingengagement between the pattern plate and face of the drum during thepassage of the carrier around the latter, and to maintain the patternplate in a substantially horizontal position as soon as possible afterleaving the drum and during its passage through the curing oven. Thislast function of maintaining the pattern plate horizontal is effectedwith the aid of a pair of supplementary sprockets 56 which are mountedon individual stub shafts 58 adjacent to the driving sprockets 26, andwhich engage the supporting rollers 49 of each carrier, serving to liftthe carrier in approximately a horizontal position from the lowercarrier supporting track section 57 onto the upper carrier supportingtrack section 50.

The drive for the machine imparts simultaneous rotation both to the pairof driving sprockets 26 and to the pair of supplementary sprockets 56and is schematically shown in Fig. 10.. A motor 32 drives an inputpulley 33 of a reducer 34 through a belt 37, the output pulley 38 of thereducer being connected to an input pulley 69, located on the side ofthe machine, by a belt 42. The input pulley 69 of the machine is securedto an input shaft 43, which also carries an input pinion 44. This shaftprojects from a gear box 47 which is attached to the side of the machineand includes a pair of gears in simultaneous engagement with the inputpinion 44. One of these gears, 54, is keyed to one end of the crossshaft 24, and the other gear 59 is keyed to the end of one of the stubshafts 58. A similar gear box 47a is mounted on the opposite side of themachine and includes a similar set of gears with the exception that thegear 54a secured to the opposite end of the cross shaft 24 drives thegear 59a attached to the end of the other stub shaft 58 through a pinion44a, acting as an idler. Fig. l discloses that the motor 32 and reducer34 are mounted upon supporting frame members 68 located at theright-hand end of the machine just below the bottom wall 14 of the oven.The motor and reducer are standard commercial units and the design ofthe gear boxes 47 and 47a follows conventional practice. Hence, theseparts are not shown in detail.

A quantity of the pulverant mold forming material i contained within thedrum 41 which is constructed so that the supply can be continuouslymaintained through the operation of a conventic nal type auger conveyor60. A coating of this material is deposited upon each pattern plate,which is brought to the drum directly from the oven in a heatedcondition. Curing of this coating is effected in the oven which isequipped with'upper and lower gas pipes 60 and 61, each carrying aseries of burners 62 (see Fig. 2), and which also includes a circulationsystem. This system includes a number of exhaust passages 86 (seeFig. 1) located in the oven top wall It) interconnected by a suitablemanifold 89 to an exhaust stack 94. Inlet openings of the system includethe two main lower openings between the oven bottom panels 13 and 15 andpanels 15 and 14, together with supplementary openings 90 provided inthe oven side panels 11. These supple-- mentary openings (see Fig. 2)are located at about the level of the tracks 35 for the roller chains 25and direct cooling air over the chains, which travel in ducts 98 formedby panels of insulating material 99. The ducts 98 thus shield the chainsfrom the heat and also act to direct and confine the supplementary aircirculation to the chains. A blower 185, schematically illustrated inFig. 1, is preferably located in the exhaust stack 94 to control theamount of air circulation.

The carriers come off the take-up sprockets 27 in an inverted positionand then pass by a knockout station defined by two pairs of wedge shapedcams 63 and 64. The construction of each pattern plate assembly includesa knockout plate 65 equipped with two pairs of rollers 66 and 67, therollers 66 contacting the cams 63 and the pair of rollers 67 contactingthe cams 64, these contacts corresponding pair of rollers are spacedlaterally (see Figs. 4 and 10 in adition to Fig. 1). This contact freesthe shell-like mold from the pattern plate and the carrier then passesonward to the drum to repeat the process.

Further details and additional constructional features of the machinewill be found in the description of the principal operating componentsthereof which follows, this description beginning with the constructionof the carrier, then the pattern plate assembly, and finally therotating drum.

Carrier The construction of the carrier is shown in Figs. 7 to 9, withadditional details being illustrated in Fig. 10 which shows the carrierin assembled relationship with a pattern plate assembly. Each carrier isconnected to the cross bar 46 by a pair of L-shaped brackets 70 whichare welded to the cross bar in spaced relationship. An L-shaped (Fig. 9)carrier side rail 71 is connected to each of the brackets 70, and aplate 72 having a downturned flange 73 is connected between the brackets70 and side rails 71 and to the cross bar 46. The flange 73 of the plate72 forms the inner end Wall of the carrier, as shown in Fig. 8. Thefront end wall of the carrier is a gate formed by a channel member 74which is connected to the left-hand side rail 71 of Fig. 7 by a hinge75. A latch 76, in the shape of a bell crank, is pivoted at 77 to alatch mounting member 73 carried by the swinging end 79 of the gate 74.The striker 80 of the latch 76 engages a keeper 81 secured to theright-hand side rail 71.

The carrier supporting rollers 49, each of which is mounted on asupporting bracket 82, are fastened to each of the carrier side rails71. These rollers 49 are composed of two independently rotatablecylindrical members, one 83, of large diameter, which engages thesupporting tracks, such as the track 85 shown in Fig. 10, and a secondcylindrical member 84 of smaller diameter. This second cylindricalsurface engages the teeth of the supplemental sprocket wheels 56 (seeFig. 1), and, when so engaged, the member 83 is free to rotate along thetrack sections 51 and 53 adjacent the sprocket Wheels 56.

The two carrier side members 71 together with the end member 73 and endgate 74 form an open rectangular frame, dimensioned to freely receive apattern plate assembly which is normally supported only at each of thefour corners of the open frame of the carrier upon a plunger 87,slidably mounted in a supporting post 88. A sectional View of theconstruction of one of these plungers 87 and its supporting post 88 isgiven in Fig. 10, which shows that the plunger 87 is slidably mountedwithin a bore formed in the post 88. A spring 91 is positioned betweenthe bottom of the bore and the undertace of the plunger 87, and a stoprod 92, secured to the plunger, extends through an opening formed in thelower face of the post and receives a nut 93. This stop rod serves tolimit movement of the plunger outwardly of the bore of the post 88 andthe nut 93 permits the plunger to be adjusted to the proper height andthe spring 91 to be preloaded to the desired extent. A channel member 95is secured to each of the carrier side rails 71 to reinforce the latterand has its upper flange 96 positioned at a spaced distance below theinturned flange 97 of the L- shaped side rail 71 to form a slide for thesupport of each pattern plate assembly during its insertion into orremoval from the carrier frame. Each plunger is adjusted so that thenormal level of its outer surface conforms to the level of the flange96.

Pattern plate assembly No plan view of the pattern plate assembly isincluded in the drawings, since in plan the configuration of thisassembly conforms to the shape of the rectangular opening defined by theside and end members of the carrier. Fig. 10 discloses theconstructional details of this assembly in end elevation, andillustrates the relationship between this assembly and the carrier withthe parts in inverted position.

The pattern plate assembly consists of two main elements, a patternplate 100 and the knockout plate 65. The pattern plate 100 has an uppersurface 102 on which the pattern for any particular object to be cast isformed. This surface 102 is bounded on all four sides by a raised borderwhich forms a frame 103. Side portions 104 depend from the frame 103and, at each corner of the frame, terminate in enlarged supportingbosses 105 which project outwardly beyond the side portions 104 to forma carrier engaging flange 106. Formed integrally with the side portions104 and bosses 105, and extending be tween the latter, is an angle framesection 119 (appearing in right side of Fig. 10) which forms acontinuation of the carrier engaging flange 106. The lower surface 107of the bosses 105 is adapted to contact the plungers 37 of the carrierwhen the pattern plate assembly is properly positioned in the carrier,and the flange 96 of the side rails thereof, during the operation ofinserting or removing the pattern plate assembly.

The knockout plate 65 is connected to the pattern plate 100 by fourguide posts 101 located at each corner of the assembly and slidablyengaging an elongated sleeve 108 formed with the pattern plate 100. Eachguide post 101 has an enlarged head 109, adapted to fit within a recess110 formed in the surface 102 of the pattern plate 100, the other end ofthe guide post being firmly connected to the knockout plate by athreaded stud 111 and nut 112. The knockout plate is engaged between thenut 112 and a shoulder 113 formed at the end of the guide post. A seriesof knockout plungers 115 are secured to the knockout plate 65 in asimilar manner, and each slidably engage a sleeve 116 formed as part ofthe pattern plate 100. A number of springs 117 are employed, one mountedaround each knockout plunger between the knockout plate 65 and the innerend 118 of the sleeve 116. These springs serve to return to the knockoutplate from the actuated position shown in Fig. 10 to a normal positionsuch as shown in Fig. 3, this normal position being defined by theengagement between the head 109 of the guide posts 101 and the patternplate.

Each knockout plate 65 carries the t'uo pair of rollers 66 and 67. Onepair of these rollers is mounted on the knockout plate adjacent each endand toward the corners of that end of the plate with the pair of rollers66 being mounted inboard of the location of the rollers 6'7. The lateralspacing between a roller 66 and roller 67 on one side of the patternplate is also reflected in the location of the two pair of knockoutearns 63 and 64 so that simultaneous contact may be established betweenall four rollers and all four knockout cams.

Rotating drum assembly The constructional details of this assembly areshown in Figs. 3 and 4, Fig. 3 being a section taken through therotational axis of the drum, and Fig. 4 a section taken perpendicular tothe rotational axis thereof. T he drum illustrated is a four-sided typeand the drum structure itself consists of two end plates 129, eachhaving four sides and a central aperture. A portion of each of threeside faces of the drum is closed by a plate 123., the fourth face, whichis uppermost in Pig. 4, being partially closed by a plate 122 incombination with a dreamout door 123, which is slidably carried innotches or grooves formed in cross members 124. Plates 121, 22 and thecross members 124 are connected between the end plates 129.

The construction of the remaining portion of each face of the drum issimilar and consists of a frame of rectangular tubing 125 connected tothe end plates 12d and to the adjacent side plates 121 and 122, or crossmember 124. A rectangular sealing plate 126, formed as a frame with aninternal opening 127, is secured to the outer face of each frame 125 oftubing, with contact between the drum and pattern plate 1% beingestablished between the outer face of this sealing plate 126, and thesurface of the frame portion 103 of the pattern plate res.

In Fig. 4 the rotation of the drum in operation is counterclockwise, anda transverse baffle plate 128 is connected between the end plates 120 ofthe drum at each advancing corner thereof to prevent powdered materialfrom piling up excessively in the corners.

Referring to Fig. 3, the center aperture in the left-hand end plate 120of the drum is sealed by a cover plate 130, which is connected by bolts131 to a cylindrical cap 132 having a flange 133 connected to the endplate 129 by a series of bolts 134. The cap 132 also has an outer flange155 which serves as a mounting ring for the left-hand drum sprocket 4G,and which extends inwardly at 136 to a hollow stub shaft 137, the shaftbeing formed with the end cap 132 and rigidly braced by a series ofgussets 138. This shaft 137 is journaled in a conventional hearing 139supported upon suitable framework, including a transverse member 14! towhich it is connected by bolts 141.

At the right-hand end of the drum the central aperture in the end plate120 is surrounded by another end cap 143, having an inner flange 144which is connected to the end plate 120 by a series of bolts 145, andalso having an outer flange 146 which serves as a mounting ring for theright-hand drum sprocket 49. Bolts 147 connect the sprocket 4b to theflange 146. The outer portion of the end cap 143 is machined at 148 toform a circular bearing race and, this hearing race, as shown in Fig. 5,is engaged by a number of rollers 149. In the construction illustrated,four roilers are employed to rotatably support the end cap 143, each ofthese rollers being journaled in a bracket which includes a pair ofupright members 15%] and a base 151 which is adapted to be attached to aframe member by bolts 152. One pair of the rollers 149 can thus bemounted upon each of the upper and lower horizontal frame members 153and 154 shown in Fig.

This construction of the end cap 143, and its mounting, provides a largeopening for continuous access to the interior of the drum proper, andpermits the employment of some means, such as the auger type conveyor 60illustrated, for continuously replenishing the supply of pulverantmaterial carried within the drum. This construction also permits theinclusion of means for elfecting the continuous screening of thepulverant material and the removal of any lumps of excessive size. Theconstruction employed for this purpose consists first of a removabletray 156, which extends through the mouth of the end cap 143 and intothe center of the drum, and is supported upon a pair of angle ironbottom rails 157, augmented by side rail members 153. The mounting ofthis supporting structure for the tray 156 is shown in Fig. 5 andconsists of two vertically extending Z-shaped frame members 159 to whichthe bottom and side rails 1 57 and 158 are attached, these frame members159 being connected by bolts 160 to lugs 161 carried by the outer sideplates 15?; of the brackets for the rollers 149. The tray has an outerend member 162 which projects beyond the sides and bottom of the trayand by contact with the frame member 159 and bottom rails 157 preventsthe tray from being inserted too far into the drum.

The interior of the drum is compartmented by four transversely extendingsections of screening 164, which, as the drum rotates, continually siftthe pulverant material therein. Any lumps of material not broken up bythe sifting action of the screens will be conveyed thereby upwardly outof the mass of material and dropped upon the tray 156 as the drumrotates.

The drum construction includes a cooling system (see Fig. 3) comprisingan inlet connection 166 and outlet connection 167, to concentric outerand inner sleeves 168 and 169 carried by the stub shaft 137. The innersleeve 169 forms the inlet coolant passage and is connected by an elbow1'70, a length of pipe 171, a union 172, a pipe 173, a second elbow 174,and a nipple 179 to one of the square tubular frames 125. An outletconnection 17S leads from the opposite side of this frame to the nextframe, and these connections between the frames are repeated until allfour frames 125 have been connected in series in the coolant system. Anoutlet connection 180 is shown leading from the last frame 125 in theseries through an elbow 176, a pipe 177, a union (not shown), and a pipe178 to a cap 181 connected to the outer sleeve 168. A coolant passageextends from this outer sleeve to the outlet connection 167.

constructional and operational features Many features result from thegeneral construction of he machine and of its individual componentswhich contribute to the successful operation of the machine and theperformance of its function of forming molds for the production ofcastings by the shell molding process. These features will be brieflydescribed, with emphasis placed upon the structure which contributes totheir presence.

A machine of the present type is designed to achieve high volumecontinuous production of shell molds. Its capacity is a function of thesize of pattern plates that can be received by the carriers and its rateof production is determined mainly by the size of the oven, since acertain amount of time must be allowed for the proper curing of eachmold. Within the limits of pattern plate size, molds for many types ofarticles can be produced by the machine at one time.

A great many features arise from the construction of the carriers whenrelated to the means provided for their propulsion and support. Aspointed out in the description of the carrier construction, the crossbar 46 which establishes the point of connection between the carrier andthe propelling conveyor chain is located away from the main body orreceptacle of the carrier. The connection between each carrier and eachconveyor chain is a pivotal one, and the cross bar 46 is located so thatthe pivotal axis of this connection lies substantially in the same planeas does the outer face of the pattern plate 100. The supporting wheels49 of each carrier are secured thereto at a point near the center ofgravity thereof and are positioned closely adjacent to the sides of thepattern plate supporting frame of the carrier.

As a result of this construction the main function of the conveyor chainbecomes one of propelling the carriers through the machine, the functionof supporting their weight being contributed principally by thesupporting wheels 49 in combination with the independent tracks whichthey engage. This permits the position of the carrier to be positivelyestablished along all points of their path of travel by rigid tracks,with the flexible conveyor chain merely acting in a contributory way tothe establishment of carrier position. Flexibility and stretch of theconveyor chains thus become a minor problem.

As the carriers approach and pass around the drum 41 the pivotal axis oftheir attachment with the conveyor chain established along their crossbar 46 becomes defined with relation to the open faces or sealing plates126 of the drum by the diameter of the sprockets 40 and the location ofthe teeth of these sprockets. Here, the diameter of the drum sprockets40 and the placement of their teeth is such that the relationshipbetween the pivotal axis of each carrier and the face of the patternplate supported thereby is maintained with respect to the sealing plates126 of the drum in such a way that the pivotal axis is substantially inthe same plane as the face of the drum opening. This means that themotion of the carrier in approaching sealing engagement with the drum,and in breaking this engagement, approaches a true hinge action, withthe carrier pivoting like a door through a relatively large are. For agiven size of the parts this permits patterns of maximum draw to bebrought into and removed from sealing engagement with the drum withoutinter ference, and, as the carriers are approaching the drum for sealingengagement therewith this permits the gradual application of sealingpressure to the carrier to urge the pattern plate frame face 103 intofirm engagement with the sealing plate 126 of the drum.

This sealing pressure is applied to the carrier through the supportingrollers 49 in passing along the section 188 of the supporting trackwhich will be referred to as a pressure section. The application of thissealing pressure effects a firm seal between the pattern plate surface103 and sealing plate 126 with the aid of the resilient mounting of thepattern plate assembly upon the four supporting plungers 87 of thecarrier and the supporting springs 91 for these plungers. The sealingpressure is maintained by the portion 52 of the supporting track whichis concentric with the axis of rotation of the drum. The creation andmaintenance of sealing pressure is aided by the fact that the carriersupporting wheels 49 are located closely adjacent to the body of thecarrier, or carrier side rails 71, for this location of the supportingwheels 49 places the supporting tracks 52 in close vertical relationshipto the area where sealing pressure must be created and maintained, ascan be seen from the disclosure of Fig. 3.

While it has been stated that the conveyor chains have the primaryfunction of propelling the carriers, they also play a part inestablishing the position or attitude of the carriers along their pathof travel through the machine, and also play a part in the establishmentand maintenance of proper sealing engagement between the pattern plateand faces of the drum. Maintenance of carrier attitude, in so far as theconveyor chains are concerned, results from the fact that roller typechains are employed and the additional fact that with a chain of thistype, independent tracks can be utilized to support the chain and defineits path of travel along all points intermediate the sprockets of themachine. Proper functioning of the chain with respect to the sealingengagement between a pattern plate and drum face is insured by thetake-up sprockets 27, which together with the movable framework 29 onwhich they are mounted, insures the maintenance of proper chain tensionand hence the proper degree of engagement between the chain and thesprockets 40 of thedrum.

The drum construction includes features which contribute to thedepositing of a proper layer of mold forming material upon patternplates continually passing through this portion of the machine. Thesefeatures include the large, open month end cap 143 and the externalroller bearings 149 therefor, which permit the insertion of means suchas the auger conveyor 60 for continuously supplying material to thedrum, and means such as the removable tray 156 which, acting inconjunction with the transverse screens 164 insures the proper siftingof material supplied to the drums and the removal of any objectionablylarge particles or impurities therefrom. The ability to continuouslysupply material to the drum means that the amount of material in thedrum can be uniformly maintained at a level where proper coating of thepatterns is effected, and also results in reducing the dust problem.

If for any reason it becomes necessary to clean out the drum, thesliding door 123 can be removed, and all material will fall out of thedrum as its rotation continues. The battle plate 190 acts to funnelmaterial through the cleanout opening, and also performs the samefunction as the baffle plates 128 when the cleanout opening isclosed-that of insuring a better distribution of material in the drum,the elimination of pockets of material in the corners, and theconsequent depositing of a uniform layer of material over the surface ofthe pattern plate.

As was mentioned in the introductory portion of the specification, oneof the properties of the mold forming material employed in the shellmolding process is that of adhering to a hot surface. Thus, any machinedesigned to accomplish continuous shell molding must include featureswhich minimize the transfer of heat to all parts contacted by the moldforming material other than the pattern plates themselves. Otherwise, acoating of material will quickly build up on these parts to interferewith their proper functioning and require that the machine be shut downin order that they may be cleaned. No trouble will be encountered fromthis source as long as the temperature of the parts is kept below thetemperature at which the resin component of the mold forming materialbecomes tacky and adhering.

Several features of the present machine contribute to achieve thisdesired result. The most critical condition is of course encountered onthe sealing plates 126 of the drum faces, for as long as nothing isallowed to interfere with the creation and maintenance of a proper sealbetween these plates and the surface 103 of the pattern plate the moldforming material will be confined to the drum and its deposit confinedto the molding surfaces of the pattern. Positive control of thetemperature of these sealing plates is therefore obtained in the presentmachine through the tubular construction of the supporting frames uponwhich the plates 126 are mounted, and the system for cooling theseframes. Circulation of coolant through the frames 125 by the meanspreviously described will prevent the temperature of the sealing plates126 from rising to an objectionable degree, and will also prevent thetransfer of heat from the hot pattern plates to the sealing plates andthence to other parts of the drum.

The general arrangement of the machine also contributes to theelimination of difficulties arising from excessive heating of partssubjected to contact with the mold forming material, and is also suchthat heating problems generally for a machine of this type areminimized. The positioning of the drum below and separate from the ovenis important in that heat transfer from the oven to the drum parts isminimized. Also contributing to this result is the arrangement of theoven with the bottom heat confining surface 15 thereof located above thedrum. As a result of this relationship between the drum and the oven,the openings through which the carriers pass from the oven to the drumand from the drum to the oven,

11 are in the bottom of the oven so that the amount of heat losses fromthe oven through these openings is naturally minimized, due to thetendency of hot air to rise, with consequent reduction in the amount ofheat transfer from the oven to the drum.

This natural circulation is augmented in the machine by the positivemeans provided for exhausting air from the oven. With the blower 185operating, air is forced out of the exhaust stack 94 and withdrawn fromthe oven through the exhaust passages 86, carrying with it anyobjectionable fumes from the curing process, and also causing the air sowithdrawn to be replaced by air entering the oven through the bottomopenings adjacent to the drum. Transfer of heat to the drum byconvection is thus positively prevented. At the same time, this aircirculation through the oven is employed, in conjunction with the ovenconstruction including the supplementary side openings 90 and ducts 98for the conveyor chains 25, to prevent the chains from becoming heatedto a temperature at whi h any mold forming material would adhere tothem. Naturally, the chains are perhaps the most critical of theoperating parts of the machine. Their flexibility must be maintained forproper operation and, during that portion of their travel around andadjacent to the rotating drum, they are exposed to any mold formingmaterial dust that might be present. As long as the chain temperature iskept below that temperature at which the resin in the mold formingmaterial will melt, the presence of such dust will present no problem inchain operation, and such temperature control of the chains isaccomplished through the foregoing features.

One other feature of the machine contributes to its successful operationwith this desirable relationship between the location of the ovenrelative to the drum. This relation, of course, requires that thecarriers ascend into the oven after passing around the drum, and thisportion of the travel of the carriers is most critical, because of thefact that until the carriers reach the oven and the curing of themolding material begins, no positive bond exists in the material itselfand it is easily displaced from its proper position on the surfaces ofthe pattern plate. The compound mounting of each carrier, that is, itspivoted connection to the conveyor chain in combination with its supportby the rollers 49, enables carrier movement and attitude to be preciselycontrolled during this critical period to achieve a minimum probabilityof displacement of the mold forming material from the pattern surfacesupon which it has been deposited. The chain supporting track section 192and carrier supporting track section 193 which define the withdrawingmovement of the carrier from the drum are arranged to impart a gradualswinging movement of the carrier from a substantially vertical positionat the initial stage of withdrawal, to a level or horizontal positionsuch as is assumed by the carrier 194 in Fig. 1. Such a horizontalposition will provide maximum insurance against displacement of the moldforming material from the pattern surfaces in the case of most patterns,and therefore means are provided in the form of the supplementarysprockets 56 and the section of the supporting track 195 to raise thecarrier under the direct heat of the oven burners in this horizontalposition.

Another desirable feature resulting from the horizontal position towhich the carriers are brought after leaving the drum and in which theyare lifted into the oven is that a loading station for the machine isprovided at the supplementary sprocket 56 and the track sections 53. Theutility of the machine, as a tool for volume production, is naturallyincreased greatly by the fact that a pattern plate assembly can bequickly inserted in a carrier of the machine or removed therefrom.Pattern plate assemblies for a machine of this type are relatively heavyarticles; if one is replaced while the machine is in operation thepattern plate assembly being removed is in a heated condition, and areplacement assembly must be preheated.

These factors make a pattern plate assembly a relatively difficultobject to handle, but these difiiculties are minimized by placing thecarrier in a substantially level position at the loading station, for inthis position the carrier end gate can be easily opened and the patternplate assembly removed by sliding motion along the supporting plungers87 and flanges 96 of the carrier side members. With the oven end panel23 moved to its downward open position to provide access to the loadingstation, a pattern plate assembly on any carrier in a horizontalposition, such as the carrier 198 in Fig. 1, can be easily removed. Themachine would be momentarily stopped to perform this operation, but theswinging end gate 74 of the carrier and sliding engagement between thepattern plate and carrier makes the removal and replacement of a patternplate assembly so quick and simple that the machine does not have to bestopped long enough to interfere with the proper curing of molds oncarriers then passing through the oven.

It is expected that many designs of specialized machines will bedeveloped to form molds for the high volume production of a wide varietyof articles under the shell molding process, and that problems arisingin the production of particular types of castings may necessitatechanges from the specific construction of the machine disclosed herein.Such changes would of course include variations in obvious details suchas the number of pattern carriers employed, the number of patternengaging faces of the drum, and consequently the exact path of movementof the pattern carriers for proper approach to and removal from thefaces of the drum. These and other changes and modifications are withinthe scope of the present invention if embraced in the definitionsthereof contained in the appended claim.

We claim:

A rotatable container for applying a coating of pulverant material to anarticle to be coated therewith, said container including a receptacleportion having a plurality of openings in the side walls thereof, eachopening adapted to be covered by an article to be coated; characterizedby said container including a frame, means for supporting said containerupon said frame for rotation about a substantially horizontal axis, saidmeans including a hollow stub shaft projecting from one end of saidcontainer and communicating with the receptacle portion thereof, abearing surface provided on the external surface of said stub shaft,means carried by said frame for engaging said bearing surface, and meansfor the continuous screening and conditioning of pulverant materialcarried within said receptacle comprising at least one member ofmesh-like material positioned within said receptacle radially outwardlyfrom the center of said shaft and adapted to screen the material in saidreceptacle upon rotation of said container, a tray projecting into saidreceptacle through said hollow stub shaft, and means for fixedlysupporting said tray from said frame, said tray extending substantiallyalong the entire length of said mesh-like member and inwardly oftheinner edge thereof whereby material collected by said mesh-likemember will be deposited upon said tray as said member passes above thetray during rotation of said container.

References Cited in the file of this patent UNITED STATES PATENTS1,027,115 Fahnestock May 21, 1912 1,127,113 Thiemann Feb. 2, 19151,448,203 Cumfer et al Mar. 13, 1923 2,266,786 Mitchell Dec. 23, 19412,317,574 Williams Apr. 27, 1943 2,518,040 Mann L Aug. 8, 1950 2,552,194Lindsay et a]. May 8, 1951 2,630,608 Granath Mar. 10, 1953 OTHERREFERENCES The Foundry, October 1950, pages 162, 164 and 168.

